The attack prompted the World Surf League to temporarily postpone the nearby Margaret River Pro surfing contest.
The attack prompted the World Surf League to postpone the nearby Margaret River Pro global surfing contest.
In the latest attack, a man suffered minor injuries when he was bitten at Lefthanders beach, with the shark leaving significant bite marks on his surfboard.
St John Ambulance Western Australia said the injured surfer, aged in his 30s, was "conscious and breathing and being treated for leg injuries".
Although it has not been confirmed what kind of shark is believed to have attacked the man, earlier this morning Surf Life Saving Western Australia reported several sightings in the area, including a four-metre Great White.
Event organisers put the competition on hold but have not said whether the victim was taking part in the competition.
"We are placing the Margaret River Pro on hold while we work with local authorities on next steps".
"The safety of our surfers & staff is a top priority".
Surf photographer Peter Jovic watched the attack from the beach and likened it to the live broadcast of a shark attack in South Africa in 2015.
"If anyone is familiar with the Mick Fanning moment at Jeffreys Bay a couple of years ago, it was very similar to that, where a shark pretty much popped up and ended up knocking a surfer off his board", Mr Jovic told ABC radio.
'There was a lot more thrashing around.
"The World Surf League (WSL) has been alerted to a shark incident that occurred near Gracetown", a WSL spokesman said.
"Further enhanced safety measures, including ski and drone presence, will be added to the event's mitigation protocols". "After that it was hard to see what was going on".
Friends used the rope from the victim's board as a tourniquet and gave him first aid until emergency crews arrived from Margaret River within six minutes.
"All the other surfers swam to him, helped him get away from his board and leg rope and helped him get on a wave, and luckily [he] caught a wave onto the reef". Chris Boyd, 35, was killed at nearby Umbies surf break in 2013.